Neuropsychological, neuroimaging and electrophysiological research supports a crucial role of lateral prefrontal cortex (PFC) in executive control of human behavior. Altered PFC function underlies a host of debilitating developmental, neurological and psychiatric disorders. Despite significant progress in PFC research, the real-time processes supporting PFC control of human cognition remain undetermined. We propose that PFC uses oscillatory dynamics to implement cognitive control of task-dependent neural networks. To address this hypothesis we will use a unique combination of direct cortical recording in neurosurgical patients (Electrocorticography; ECoG) with superb spatio-temporal resolution and signal-to-noise ratio, along with cutting-edge analysis to define PFC-dependent neural networks supporting cognition. We will examine three tasks probing hallmarks of frontal lobe function (categorical perception, working memory and controlled vs. automatic attention) across three sensory modalities (audition, vision, touch) to address the generalizabilty of PFC dependent oscillatory network control. We will then examine the causality of the oscillatory dynamics observed with ECoG using scalp EEG and behavioral methods in patients with focal lesions centered in lateral PFC. Aim 1 will use ECoG recording to define the role of PFC control of phase locking of low frequency neural oscillations between task dependent networks and whether cross frequency coupling (CFC) between high gamma oscillations (60-200 Hz) and low frequency oscillations tracks task performance. Aim 2 is the most exploratory and draws from a recent finding in our laboratory demonstrating that an exquisite cortical microstructure observed at 4 mm cortical resolution supports categorical perception of phonemes in the temporal lobe. Using ECoG we propose to examine whether such a sub-centimeter microstructure extends to the PFC during cognitive control. Aim 3 wil examine the causality of each oscillatory process in patients with either focal lateral PFC or posterior parietal cortex (PPC) damage. We predict that deficits in neural oscillations in the lesioned hemisphere wil correlate with behavioral deficits and reveal novel patterns of neuroplasticity in the non-lesioned hemisphere. In summary, the proposed work will define the role of PFC in both distributed and local network function in the support of human behavior.